Plastic welding devices comprise usually a housing with a lower tool arranged therein as well as an upper tool arranged therein. The lower tool is fastened to a lifting table, whereas the upper tool is rigidly mounted to an upper tool plate. Further, such known plastic welding devices comprise a preheating arrangement for heating the first and the second component prior to welding. Usually, the preheating arrangement is here coupled to the lifting table. By means of the lifting table, the lower tool can be moved in the direction of the upper tool to weld a first component in the lower tool to a second component in the upper tool, especially by means of friction welding.
Such plastic welding devices are used for example in the automotive industry or in the medical technology. In the automotive industry, such plastic welding devices are used for producing lights but may be used also in the production of other components or component groups which consist of plastic or contain plastic. In a similar way, the plastic welding device may be used in the production of devices and/or component groups in the medical technology or in the production of consumer goods.
The operation of the known plastic welding devices with preheating arrangement is as follows. At first a user places a first component on the lower tool. Subsequently, he positions a second component on the first component in the lower tool. Then, the lifting table with the lower tool and the components arranged thereon moves from an initial position in the direction of the upper tool until the second component abuts the upper tool. This movement takes place along only one axis which is vertical with respect to a floor or ground on which the plastic welding device is arranged.
Then, the lifting table moves along this vertical axis back into an intermediate position in which the preheating arrangement can be arranged from a neutral position into an aligning position between the components. After the preheating arrangement has been arranged between the two components, the preheating arrangement is positioned in a preheating position by means of a new vertical movement of the lifting table so that the two components are heatable at the places to be welded. After the heating, the lifting table is moved along the vertical axis again into the intermediate position and thus the preheating arrangement back into the aligning position. After the preheating arrangement has then been moved back into the neutral position, the lifting table is moved along the vertical axis into a welding position.
Now, a welding of the first component to the second component by means of friction welding or by means of pressing the pre-heated components against each other takes place. After finishing the welding, the lifting table moves with the lower tool and the compound of first and second component arranged thereon along the vertical axis from the welding position back into the initial position. As soon as the lifting table has reached the initial position, the user may remove the compound of first and second component.
A disadvantage of the above described plastic welding device with preheating arrangement becomes apparent if components with complex protrusions or undercuts shall be heated and welded. A protrusion or undercut results in friction welding especially due to the not arbitrary variable angular position of the components to be welded with respect to each other. Especially, the two components have to be placed in the respective tool in such a way that a friction welding force can be transferred effectively to the joining portion of the respective component. Due to this not freely determinable angular position of the two components with respect to each other as well as the movability of the tools solely along the vertical axis, undercuts or protrusions result depending on the components to be welded to each other. During a movement along the vertical axis, these would lead to a damaging and/or destruction of at least one of the components and/or one of the tools or the preheating arrangement.
For eliminating this disadvantage, the company BRANSON developed in the field of friction welding a plastic welding device, the lower tool of which is arbitrarily movable on the lifting table in the space, especially along a control line. A movement of the upper tool is not possible due to the forces occurring at the vibration welding or friction welding and thus not envisaged.
However, this known plastic welding device comprises no preheating arrangement. Further, all tools arranged on the lifting table move equally, thus especially in the same direction. This can be illustrated by means of the example of a sliding table which is arranged on the lifting table. While the lifting table allows a movement along the vertical axis, the sliding table allows a movement along the axis within the x,y-plane. In practice, the sliding table allows with respect to an opening of the plastic welding device simultaneous movement forward, thus in the direction of the user, or backwards, and thus away from the user, for all tools arranged thereon. Such a controlling of the tool requires at least three drives, one for the vertical direction and two for the movement in the plane. Further, the coordinated controlling of the respective drives is complex which makes the controlling overall costly.
Further, the known plastic welding device is not suitable for the usage in welding two components to each other which are arranged mirror-symmetrical on the lower tool. The usage of the known device would especially during the simultaneous welding of two mirror-symmetrically arranged components with complex protrusions or undercuts further lead to the damaging or destruction of at least one of the components and/or the preheating arrangement or at least a preheating device of the preheating arrangement as both tools are always moved in the same direction.
At least some implementations of a plastic welding device enable components with complex undercuts to be welded easily and quickly. Further, a respective plastic welding method is provided.